The Simulation And Investigation For Flow Characteristics In Vertical Pipe Of Multiphase Exterior CFB

The gas-liquid-solid multiphase flow with heat transfer, mass transfer and chemical reaction are the base phenomenon in the chemical apparatus and chemical engineering unit operations. The multiphase flow is different from the pure phase flow. It possess complicated fluidized characters, thus the study in the laws of multiphase flow is getting one of the key problem in the chemical progress.The research of the local flow and heat transfer characteristics in the multiphase flow bed were carried out in numerical simulation and experiment. In the condition of different mass flow, temperature and pressure, the stability situation and instability situation simulation of 2D, 3D were made in the riser of circulating fluidized bed. The typical multiphase flow models----the Euler-Euler model and Discrete model were compared with each other, recurred the characteristics of CFB logically. The phenomena of particle clusters in the region near the wall of pipe was simulated and analyzed. The three factors which influence the pressure fluctuation were discussed by simulating the clusters of particles distribution of pressure and the volume fraction of particles. The formation, movement and decomposition of the clusters of particles were the main causation of the pressure fluctuation. A simple configuration model for calculating effective collision heat transfer factor of particles to wall is set up in this paper, and temperature distributing of single particle is simulated in steady states. The simulation of the clusters of particles and pressure fluctuation in a liquid-solid coarse particle fluidized bed will give optimizing and the basic understanding for stable operation of fluidized bed.